Would y'all be interested if I implemented JFR support? There's not really any official format documentation, but there's some basic docs here and an Apache licensed Java parser to steal from.

Unfortunately it's a binary format, but there's good support for binary reads in JS nowadays, so it ought to be possible.

Another complication is that JFR files can support multiple concurrent profiles, for example both an alloc and CPU profile in the same file. It's not clear what we should do given such a file.